The present inventors have already proposed carbamic acid esters represented by: ##STR2## wherein R represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R.sup.1 represents a residue of an alcohol from which an OH group is removed,
and also proposed their applications (Japanese Kokai Publications 61-275259, 61-275260 and 61-275270 corresponding to U.S. Pat. No. 4,935,413).
Japanese Kokai Publication 4-66563 (corresponding to EP-A 465,162) discloses a one step synthesis method wherein the unsaturated carbamic acid esters are prepared by reacting methacrylamide and chloroformic acid ester. However, the chloroformic acid esters are unstable and a few kind of them can be used therefor.
Japanese Kokai Publication 61-275259 also provides a process for producing the unsaturated carbamic acid esters wherein a compound having an isocyanate group, represented by: ##STR3##
(wherein R is the same as mentioned above), is reacted with alcohols. The isocyanate compound, however, is too reactive to control and treat the reaction.